Angle-selective irradiation insulation on a building envelope

ABSTRACT

In a method for producing a building envelope part ( 19 ) for angle-selective irradiation insulation on a building envelope, which building envelope part ( 19 ) has an outer surface ( 29 ), an inner surface ( 39 ) opposite the outer surface ( 29 ), and a side edge that bounds the outer surface ( 29 ) and the inner surface ( 39 ), the outer surface ( 29 ) is provided with outer structures ( 219 ) and the inner surface ( 39 ) is provided with inner structures ( 319 ). The outer structures ( 219 ) and the inner structures ( 319 ) are arranged relative to each other in such a way that the building envelope part ( 19 ) has different transparency depending on the spatial angle of incidence. The outer structures ( 219 ) and the inner structures ( 319 ) are arranged in particular with regard to an orientation of an intended application of the building envelope part ( 19 ) and with regard to the latitude of the intended application of the building envelope part ( 19 ). By means of the design of the outer structures and the inner structures according to the invention, it is possible that the outer structures and the inner structures are arranged in such a way that a building envelope comprising the building envelope part is optimally adapted to an orientation and in particular to an orientation deviating from southern orientation, to tilted or horizontal arrangements, or to an arbitrary latitude. Thus the transmittance behavior of the building envelope part can be accordingly optimized for the particular situation.

BENEFIT CLAIM

The present application claims the benefit under 35 U.S.C. 119 ofpriority from international application PCT/EP2012/061835 filed 20 Jun.2012, which claims priority to European application EP11170686.7 filed21 Jun. 2011, the entire contents of which are hereby incorporated byreference for all purposes as if fully set forth herein.

TECHNICAL FIELD

The invention relates to a building envelope part according to thepreamble of independent claim 1, as well as to a method formanufacturing such a building envelope and a computer program forimplementing such a method.

Such building envelope parts exhibit an outer surface with outerstructures, an inner surface opposite the outer surface with innerstructures, and a side edge that bounds the outer surface and innersurface, wherein the outer structures and inner structures are arrangedrelative to each other in such a way that the building envelope part hasa varying translucency depending on the spatial angle of incidence, forexample to solar radiation, and can be used in building technology forangle-selective irradiation insulation on a building envelope.

PRIOR ART

In order to specifically vary the absorbance of a building relative tosolar radiation, use is today made of building envelopes or facades withan angle-selective transmittance behaviour. In particular, anirradiation insulation that allows more or less transmittance to ariseover the seasonal variation of the sun's trajectory can be achieved inthis way. For example, this type of building envelope makes it possibleto achieve a high transmittance of direct solar radiation in winter,thereby lending support to the heating process, and a low transmittancein the summer to protect against overheating, so that cooling can bereduced. Angle-selective building envelopes or facades along withtransparent thermal insulation are optimized in terms of their seasonaltransmittance behaviour for central northern latitudes on south frontsthe building or on south facades. For example, European Standard (EN)13363 “Solar Protection Devices in Combination with Glazing—Calculationof Solar Radiation and Degree of Light Transmittance”, which was adoptedby the German Institute for Standardization (DIN), discusses spatialangles with elevations of 0° to 90° and azimuth angles of −90° to +90°for corresponding window blinds or shading elements. In this context,the term “elevation” relates to a vertical angle over a horizontalplane. The term “azimuth” in this sense relates to the deviation fromsouth, wherein an azimuth angle of −90° denotes an east orientation,−45° a southeast orientation, 0° a south orientation, +45° an southwestorientation, and +90° a west orientation. Such angle-selective buildingenvelopes often exhibit lamellar, horizontally arranged structures. Thebuilding envelopes are here angle-selective in that the transmittance ordegree of transmittance for a south orientation and varyingelevations—this direction is referred to as the transversal axis—canchange significantly as a function of the angle.

In this conjunction, building envelope parts are among other thingsfabricated as components for building envelopes that, once built in,permit an angle-selective irradiation insulation for the buildingenvelope. For example, WO 01/53756 A2 describes a glass pane as acomponent with an outer surface and inner surface, which has prismaticelevations as structures on the outer surface or inner surface. Theprismatic elevations are intended to divert light so as to outwardlyredirect steeply incident sunlight in the summer, while allowingshallowly incident sunlight to freely pass through the glass pane to theinside in the winter.

The transmittance or degree of transmittance remains approximatelyconstant or at most tapers off in border areas for a light source movingfrom east to west given an identical elevation—this direction isreferred to as the longitudinal axis. As a result, the known buildingenvelopes of building envelope parts are either unsuitable or limitedlyeffective for orientations that deviate from the south, for inclined orhorizontal configurations, for example roof surfaces, as well as forother geographic latitudes. For example, the stipulation that the solaraltitude be high in the summer and low in the winter is not applicable.In these orientations, the strongly transmitting area of the angularrange is rather traversed during sunrise or sunset, while the high solaraltitude is encountered only in a border area or not at all in theseorientations. As a consequence, the irradiation on the building is oftenvery high when the building exhibits such a known building envelope, andthe amount of irradiated energy is often significant given the longerduration of sunshine in the mornings and evenings, and can help causethe building to overheat.

Therefore, the object of the present invention is to propose a buildingenvelope part or the manufacture of a building envelope part thatenables an angle-selective irradiation insulation on the buildingenvelope for any orientations and inclinations of the building envelopepart, as well as for any geographic latitudes of the building location.

DESCRIPTION OF THE INVENTION

According to the invention, the object is achieved by a buildingenvelope part as defined by the features in independent claim 1, as wellas by a method as defined by the features in independent claim 10, and acomputer program as defined by the features in independent claim 18.Advantageous embodiments of the invention may be gleaned from thefeatures in the dependent claims.

The gist of the invention is as follows: A building envelope part forangle-selective irradiation insulation on a building envelope exhibitsan outer surface with outer structures, an inner surface opposite theouter surface with inner structures, and a side edge that borders theouter surface and inner surface, or joins the outer surface with theinner surface. The outer structures and inner structures are herearranged relative to each other in such a way that the translucency ofthe building envelope part varies as a function of the spatial angle ofincidence. The outer structures and inner structures are here arrangedat an acute angle to the side edge.

In connection with the invention, the term “building envelope part”relates to parts exposed to direct or diffuse solar radiation orartificial light, attachment or mounting elements of a building, such asfacades, façade elements, transparent thermal insulation elements (TWD),windows, roofs and porches, to energy generating systems, such asthermal, photovoltaic and hybrid collectors, as well as to targetedlight or visual guidance systems. In particular, the term “buildingenvelope part” can be construed as any suitable, preferably plate-typeconstruction having a round, triangular, square or hexagonal shape,whose border is designated as a side edge in terms of this invention,for use in a building envelope, for example a preferably structuredglass or acrylic glass pane, a plastic plate, a metallic, mineral orwooden construction or something similar. In particular, a low-ironglass can be used as the building envelope part. The building envelopepart can be configured as a one-piece component or composed of severalelements. For example, it can also be designed as laminated glass, inwhich in particular correspondingly printed glass panes are used, andprefabricated films or switchable layers are applied to panes of glass,or attached between several glass panes. In conjunction with theinvention, the term “spatial angle of incidence” is understood as theangle doublet comprised of a zenith angle between the perpendicular tothe outer surface of the building envelope part or the light incident onthe building envelope part, as well as of an azimuth angle between adefined angle of the outer structure and the perpendicularly projectedlight incident on the outer surface of the building envelope part.Without any explicit other explanations, the terms “south”, “north”,“north hemisphere”, “June 21” and “December 21” used in conjunction withthe invention refer to locations in the northern hemisphere. The latterare replaced by “north”, “south”, “south hemisphere”, “December 21” and“June 21” respectively for locations in the southern hemisphere in thesecases.

The outer structures and inner structures can extend from one side edgeto a possible other side edge on the outer surface or on the innersurface. In particular, they can also each exhibit an oblong expansion,wherein this oblong expansion can define an axis of the outerstructures. The areas of the exterior side between the outer structuresand the areas of the interior side between the inner structures canremain unchanged or unmachined and translucent. The outer structuresand/or inner structures can be covered by a protective layer as asafeguard against damaging influences, for example in the case of alaminated glass. The acute angle between the outer structures or innerstructures according to the invention relates to the plane of the outersurface or inner surface, so that it becomes particularly evident from atop view of the outer surface or inner surface. In particular, it canencompass all angles that are smaller than 90°, and especiallysignificantly smaller than 90°, i.e., for example smaller than 85°,smaller than 80°, smaller than 70°, smaller than 60°, smaller than 50°,smaller than 40°, smaller than 30°, smaller than 20°, smaller than 10°or smaller than 5°. Concurrently with acute-angled arrangement of theouter structures or inner structures and the side edge, the outerstructures and inner structures can also be arranged at an obtuse anglerelative to the side edge. For example, the sum of this obtuse angle andthe acute angle yields 180° at the tangent of the side edge.

The acute-angled arrangement according to the invention of the outerstructures or an axis thereof and the inner structures or an axisthereof relative to the side edge makes it possible to arrange the outerstructures and inner structures in such a way as to optimally adjust abuilding envelope encompassing the building envelope part to anorientation deviating from the south, to an inclined or horizontalarrangement, or to any geographic latitude. As a consequence, thetransmittance behaviour of the building envelope part can beappropriately optimized to the respective situation. For example, thecircumstances presented by a roughly east or west orientation of thebuilding envelope part can be taken into account in a relativelyeffective way. A transmittance of about 60% can take place with respectto angles of incidence typically encountered in winter, for example,while a transmittance of about 20% can take place for those typicallyencountered in summer, for example. The building envelope part typicallyhas strictly a passive effect, and can be adjusted not just to the solaraltitude and façade orientation, but rather also to the length of theheating or cooling period of a building. For example, the buildingenvelope part can further be comparatively durable as a glazing, andprovide good weather protection for the building. In addition, thebuilding envelope part can be manufactured in a comparatively costeffective manner, and visually adjusted to be suitable for residential,commercial and industrial premises. The rear section of the buildingenvelope part according to the invention can also be combined withhousing panels comprised of massive wood, other materials or structuresas the thermal capacity store and/or provided with ventilation dampersto utilize cooling through natural convection, which can be opened orclosed seasonally or as needed.

According to the invention, then, the irradiation insulation on thebuilding can be controlled to conform to the situation, wherein theouter structures or an axis thereof and the inner structures or an axisthereof to this end run inclined at a specific angle relative to a sideedge, depending on the respective celestial orientation of the providedapplication for the building envelope part and the latitude. Forexample, the solar radiation can accordingly also be used atorientations other than toward the south for heating purposes, and atthe same time offer irradiation insulation to protect againstoverheating. As may be gleaned from the aforementioned EN 13363, forexample, the latter standard is not to be used for elevations of lessthan 0°, which is factually tantamount to saying that only horizontallylying lamellae or structures can be considered according to thestandard. If the lamellae or structures are inclined, irradiationelevations of less than 0° are also possible, which lie outside theevaluation range of this standard. As a consequence, it can be inferredthat the same method can also yield clearly better results in the fightagainst overheating, especially in the summer, and in the generation ofenergy during the winter even at latitudinal lines other than theaverage and at façade orientations other than toward the south. Since acomparatively finely resolving angular function can be taken intoaccount in the building envelope part according to the invention, thefocus can be placed on situations with more than one heating and/orcooling period. In addition, the building envelope part according to theinvention can also be configured to serve as angle-selective,situation-adapted irradiation insulation for artificial light.

In one exemplary embodiment of the building envelope part, the outerstructures are designed as light diffusers, and the inner structures aredesigned as optically opaque. In this conjunction, the term “lightdiffusers” relates in particular to structures that diffusely scatterincident light. For example, the outer structures as light diffusers canbe applied to the glass pane through printing, etching, sandblasting,roughening, as a film or in some other way. As a consequence, theangle-dependent transmittance can be achieved via the diffuselyscattering, e.g., printed, sandblasted, etched or roughened outerstructures and reflecting or absorbing inner structures, and optimizedfor the exact requirements. For example, optically opaque structures canbe applied to the building envelope part through printing, as a film orin some other way, especially if the building envelope part is designedas a glass or acrylic glass pane. Outer structures and inner structuresconfigured in this way make it possible to scatter the solar radiationincident on the exterior side of the building envelope part in aspecific first spatial angle of incidence range on the outer structuresin such a way that at least a portion thereof is deflected on theoptically opaque inner structures while penetrating the building part.This allows additional solar radiation other than the solar radiationdirectly incident on the optically opaque inner structures in the firstspatial angle of incidence range to be incident on the optically opaqueinner structures, which can in particular elevate the radiationinsulation, for example in the summer. At the same time, the outerstructures and inner structures configured in this way can scatter thesolar radiation incident on the exterior side of the building envelopepart in a specific second spatial angle of incidence range in such a waythat at least a portion thereof is guided between and through theoptically opaque inner structures while penetrating the building part.This allows additional solar radiation other than the solar radiationthat passes directly by the optically opaque inner structures topenetrate through the building envelope part in the second spatial angleof incidence range, which in particular can diminish the irradiationinsulation, for example in winter.

In another exemplary embodiment, the outer structures are prismatic, andthe inner structures optically opaque in design. When the outerstructures and inner structures are configured in this way, the solarradiation incident on the external side of the building envelope part ina specific first spatial angle of incidence range can be bundled on theouter structures in such a way that at least a portion thereof isdeflected on the optically opaque inner structures while penetratingthrough the building envelope part. This allows additional solarradiation other than the solar radiation directly incident on theoptically opaque inner structures in the first spatial angle ofincidence range to be incident on the optically opaque inner structures,which can in particular elevate the radiation insulation, for example inthe summer. At the same time, the outer structures and inner structuresconfigured in this way can bundle the solar radiation incident on theexterior side of the building envelope part in a specific second spatialangle of incidence range in such a way that at least a portion thereofpasses the optically opaque inner structures while penetrating thebuilding part. This allows additional solar radiation other than thesolar radiation that passes directly through the optically opaque innerstructures to penetrate through the building envelope part in the secondspatial angle of incidence range, which in particular can diminish theirradiation insulation, for example in winter.

In the two exemplary embodiments of outer structures and innerstructures described above, the optically opaque inner structures can beconfigured as light reflectors. For example, the inner structures can bedesigned as a mirror coating, such as a printed silver layer, an opaquecoloration or a geometric, reflecting structure, in particular in glasspane-like building envelope parts. This allows the irradiation incidenton the inner structures in particular in the first spatial angle ofincidence range to be reflected via the outer surface out of thebuilding envelope part. As a result, the building envelope part can bekept deeply heated. As an alternative, the optically opaque innerstructures in the mentioned two exemplary embodiments of outerstructures and inner structures described above can be configured aslight absorbers, wherein the light absorbers are preferably photovoltaiclight absorbers. This makes it possible to prevent radiation incident onthe inner structure from penetrating through the building envelope parton the one hand, while the energy of the irradiation to be insulated canbe used for photovoltaic power production on the other, in particular inthe summer. Light bundling allows this to happen with a high efficiency.

In another exemplary embodiment, the outer structures are designed to belight polarizing in a first way, and the inner structures are designedto be light polarizing in a second way complementary to the first way.This type of configuration for the outer structures and inner structuresmakes it possible to completely cancel out direct radiation at certainangles of irradiation. Given the other extreme, i.e., at certain otherangles of irradiation, a transmittance of about 50% relative tonon-polarizing inner and outer structures can be achieved, for example.Comparatively high contrast ratios can be achieved as a result.

In particular the outer structures can also be designed as athree-dimensional structure, for example an inclined flank, as a resultof which both the degree of transmittance and reflection can be elevateddepending on the angle of irradiation. The outer structures and innerstructures can also be contiguous in design, for example have anL-shaped cross section. The outer surface and/or inner surface can beprovided with anti-reflective coatings, making it possible to increasethe degree of transmittance. The outer surface and/or inner surface canbe provided with wavelength-selective infrared reflectors, as a resultof which the heat dissipation of the underlying building envelope layercan be reduced without significantly diminishing the degree oftransmittance for visible light.

The outer structures preferably encompass parallel stripes arranged in acommon plane, and the inner structures encompass parallel stripesarranged in a common plane. The stripes of the outer structures and thestripes of the inner structures can here each exhibit straight sides anda fixed width. This type of configuration for the outer structures andinner structures enables a comparatively simple, expedient constructionof the building envelope part. The outer structures are here preferablyarranged parallel to the inner structures, wherein the common plane ofthe outer structures and the common plane of the inner structures aredifferent. The stripes of the outer structures and the stripes of theinner structures are here established by mathematical expressions thatcorrelate the variables r, d, m, c, α_(±) and n, and are preferablyformulated according to the equations

$\frac{r}{d} = {\frac{\sin \left( \alpha_{+} \right)}{\sqrt{n^{2} - {\sin^{2}\left( \alpha_{+} \right)}}} - \frac{\sin \left( \alpha_{-} \right)}{\sqrt{n^{2} - {\sin^{2}\left( \alpha_{-} \right)}}}}$

and m=c=r, wherein m is the width of one of the stripes of the outerstructures, for example in [mm], r is the width of one of the stripes ofthe inner structures, for example in [mm], c is the distance between thestripes of the outer structures, for example in [mm], d is the thicknessof the building envelope part, for example in [mm], n is the averagerefraction index of the building envelope part, α⁻ is the projectedangle of incidence for light to be insulated, and α₊ is the projectedangle of incidence for light not to be insulated. This type ofconfiguration for the outer structures and inner structures enables acomparatively efficient, readily calculable construction of the buildingenvelope part.

The outer structures are preferably arranged in a directionperpendicular to the outer surface and inner surface, offset in relationto the inner structures. Because the outer structures and innerstructures thus do not lie on top of each other, angle-selectiveirradiation insulation can be efficiently achieved by the buildingenvelope part. The angular ranges in which the irradiation is to beinsulated or not insulated can be comparatively easily adjusted bysuitably selecting the offset for the outer structures in relation tothe inner structures in the direction perpendicular to the outer surfaceand inner surface.

The acute angle preferably ranges between about 25° and about 55°, orabout −55° and about −25°. With such an acute angle, an optimizedbuilding envelope part can be fabricated in particular for Europeanlatitudinal lines, and especially for building envelope parts orientedtoward the east or west. Smaller angles are best used for buildingenvelope parts more strongly oriented toward the south, while largerangles are best used for building envelope parts more strongly orientedtoward the north.

The building envelope part preferably exhibits an essentiallyrectangular shape with four side edges. This type of basic shape for thebuilding envelope part enables a comparatively simple manufacture, aswell as a comparatively simple, efficient integration into a buildingenvelope. The side edge arranged at an acute angle in relation to theouter structures or an axis thereof and the inner structures or an axisthereof is here preferably essentially horizontally aligned in aprovided application for the building envelope part.

The outer structures and inner structures are preferably essentiallylamellar in design. For example, the term “lamellar” can be understoodas a parallel arrangement of stripes in a plane, wherein these stripesexhibit straight sides and a certain width. This type of lamellarconfiguration for the outer structures and inner structures enables acomparatively simple, efficient construction and manufacture of thebuilding envelope part.

The building envelope part according to the invention described abovecan also be used for artistically designing the building envelope or forother visual purposes by adjusting the outer structures and innerstructures so that a desired graphic pattern of whatever geometrydesired can be achieved, e.g., via discontinuous stripes or dot-likepatterns, or by using colour adjusted building envelope parts. Whilethis allows for numerous possibilities in relation to the artisticdesign of the facades, it can also easily have a negative influence onthe contrast ratio for the structures. Striped structures in atransverse direction can also generate a Moire Effect. When passing infront of a façade equipped with such a building envelope part, theseMoire stripes can wander along, so that corresponding effects can beused in targeted fashion. Likewise, the building envelope part can giverise to wavelength-dependent effects at the boundaries of lightdiffusing to right on the outer surface owing to the colour dispersionof direct radiation during reflection on the inner surface of the glass,as a result of which the blues or reds of the spectrum can be reflectedor filtered out. This can slightly alter the hue of the reflected andtransmitted light, and targeted use can be made of the correspondingeffects. In addition, the direct portion of reflection can essentiallybe eliminated by suitably selecting the shape and position of the outerstructures and inner structures. This can be of interest with respect tothe appearance of the building, or so as to avoid disturbing reflectioneffects. In addition, for example, building envelope parts designed asglass panes can offer an infinitely variable screen, and the essentiallydull effect produced by the glass surface itself can prevent accidentsthat involve flying birds, even given a comparatively low dullnessportion. For example, the building envelope part can be mounted asfaçade glass in front of windows, opaque walls and insulations or infront of transparent insulation (TWD). Any air space between the glassand façade lying behind it can be naturally or artificially ventilated,or used for generating energy. For diffuse, i.e., non-direct solarradiation, the building envelope part can exhibit an elevatedtransmittance for diffuse light, for example, which can be advantageousin the summer during bad weather, which creates a demand for heatingenergy.

Another aspect of the invention relates to a method for manufacturing abuilding envelope part for angle-selective irradiation insulation on abuilding envelope, such as a building envelope part of the kinddescribed above, wherein the building envelope part exhibits an outersurface, an inner surface opposite the outer surface, and a side edgethat borders the outer surface and inner surface or joins the outersurface with the inner surface. The outer surface is provided with outerstructures, and the inner surface is provided with inner structures,wherein the outer structures and inner structures are arranged inrelation to each other in such a way that the building envelope partvaries in translucence depending on the spatial angle of incidence. Thearrangement of the outer structures and inner structures includes theorientation of a provided application for the building envelope part andthe latitude of the provided application for the building envelope part.In this conjunction, the term “provided orientation” relates to thealignment and inclination in which the building envelope part is to beincorporated, for example in which it is to be built into a buildingenvelope. In this conjunction, the term “provided latitude” relates inparticular to the location of the place at which the building envelopepart is to be used or applied.

The method according to the invention allows the individualizedmanufacture of a building envelope part, so that the highest possibleefficiency in application can be achieved. In particular, the methodaccording to the invention also makes it possible to efficientlyimplement the advantages described above in conjunction with thebuilding envelope part according to the invention.

The longitudinal axes of the outer structures and inner structures arepreferably aligned parallel to an intersecting line between the plane ofthe solar ecliptic and the plane of the building envelope part in theprovided application if the building envelope part can be reached bydirect solar radiation on all days of a calendar year in the providedapplication. This enables a comparatively efficient usage for this typeof application for the building envelope part. The acute angle betweenthe outer structures and side edge or between the inner structures andside edge is here established for building envelope parts inclinedhowever desired by a mathematical expression that correlates thevariables ω, β, γ and φ, preferably according to the equation

$\omega = {{- {{sgn}\left( {\varphi*{\sin (\gamma)}} \right)}}*\arccos {\quad\left( \frac{{{\sin \left( {\varphi } \right)}*{\sin (\beta)}} + {{\cos \left( {\varphi } \right)}*{\cos (\beta)}*{\cos (\gamma)}}}{\sqrt{\left. {{{\cos \left( {\varphi } \right)}*{\cos (\beta)}} + {{\sin \left( {\varphi } \right)}*{\cos (\gamma)}*{\sin (\beta)}}} \right)^{2} + {{\sin^{2}(\gamma)}*{\sin^{2}(\beta)}}}} \right)}}$

and for vertically inclined building envelope parts by a mathematicalexpression that correlates the variables ω, γ and φ, preferablyaccording to the equation

${\omega = {{- {{sgn}\left( {\varphi*{\sin (\gamma)}} \right)}}*{\arccos\left( \frac{\sin \left( {\varphi } \right)}{\sqrt{1 - {{\cos^{2}(\varphi)}*{\cos^{2}(\gamma)}}}} \right)}}},$

wherein ω is the acute angle, β is an inclination (vertical: β=90°) andγ is an alignment (south: γ=0°, west: γ positive) of the buildingenvelope part and φ is the latitude (equator: φ=0°, north hemisphere: φpositive) in the provided application. Such a calculation method can beused to precisely dimension the building envelope part for the furthertype of application in a comparatively simple manner.

The longitudinal axes of the outer structures and inner structures arepreferably aligned perpendicular to an intersecting line between theplane of the solar ecliptic and the plane of the building envelope partin the provided application if the building envelope part cannot bereached by direct solar radiation on all days of a calendar year in theprovided application. For example, this condition can be satisfied onthe northern hemisphere if the building envelope part is aligned towardthe north. This also enables a comparatively efficient usage for thisadditional type of application for the building envelope part by havingthe degree of transmittance for the projected angle of incidence be assmall as possible during sunrise and/or sunset, and otherwise as largeas possible to utilize the diffuse sunlight in winter.

A first projected angle of incidence with a maximum light transmittancethrough the building envelope part is preferably established. The firstprojected angle of incidence is preferably established taking intoaccount the projected angle of incidence on December 21 in the providedapplication of the building envelope part, which can be expedient inparticular for a provided application of the building envelope part onthe northern hemisphere. The first projected angle of incidence isestablished by a mathematical expression that correlates the variablesα₊, β, γ, ε and φ, preferably according to the equationα₊=arcsin(cos(φ)*cos (γ))+(β−90°)−ε, wherein α₊ is the first projectedangle of incidence, β is an inclination and γ is an alignment of thebuilding envelope part in the provided application, and ε is theobliqueness of the ecliptic relative to the equator. In particular, εcan be about 23.4°. Given such a first projected angle of incidencecalculated in particular using this equation, the building envelope partcan comparatively easily be dimensioned so as to efficiently establish aspatial angle of incidence range intended to allow as much transmittancethrough the building envelope part as possible.

A second projected angle of incidence with a minimum light transmittancethrough the building envelope part is preferably established. The secondprojected angle of incidence is preferably established taking intoaccount the projected angle of incidence on June 21 in the providedapplication of the building envelope part, which can be expedient inparticular for a provided application of the building envelope part onthe northern hemisphere. The second projected angle of incidence isestablished by a mathematical expression that correlates the variablesα⁻, β, γ, ε and φ, preferably according to the equationα⁻=arcsin(cos(φ)cos(γ))+(β−90°)−ε, wherein α⁻ is the second projectedangle of incidence, β is an inclination and γ is an alignment of thebuilding envelope part in the provided application, and ε is theobliqueness of the ecliptic relative to the equator. Given such a secondprojected angle of incidence calculated in particular using thisequation, the building envelope part can comparatively easily bedimensioned so as to efficiently establish a spatial angle of incidencerange intended to allow as little transmittance through the buildingenvelope part as possible.

The building envelope part is preferably configured in such a way thatthe outer structures in a common plane encompass parallel arrangedstripes, and the inner structures in a common plane encompass parallelarranged stripes. The stripes of the outer structures and innerstructures can each exhibit straight sides and a fixed width. This typeof configuration for the outer structures and inner structures enables acomparably simple, efficient construction of the building envelope part.The building envelope part is here configured in such a way that theouter structures are arranged parallel to the inner structures, whereinthe common plane of the outer structures and common plane of the innerstructures are different, and that the stripes of the outer structuresand stripes of the inner structures are established by a mathematicalexpression that correlates the variables r, d, α_(±) and n, preferablyformulated according to the equation

${\frac{r}{d} = {\frac{\sin \left( \alpha_{+} \right)}{\sqrt{n^{2} - {\sin^{2}\left( \alpha_{+} \right)}}} - \frac{\sin \left( \alpha_{-} \right)}{\sqrt{n^{2} - {\sin^{2}\left( \alpha_{-} \right)}}}}},$

wherein r is the width of one of the stripes of the inner structures,for example in [mm], d is the thickness of the building envelope part,for example in [mm], n is the average refraction index of the buildingenvelope part, α₊ is the first projected angle of incidence, and α⁻ isthe second projected angle of incidence. This type of configuration forthe outer structures and inner structures enables a comparativelyefficient, readily calculable construction of the building envelopepart. The building envelope part is preferably configured in such a waythat a width of the stripes of the exterior side, a width of the stripesof the interior side, and a respective distance between the stripes areessentially identically dimensioned. This type of configuration canyield a preferred contrast ratio, wherein it is also possible to deviatefrom such a configuration, for example, if the building envelope part inits provided application is preferably to have heating or coolingproperties.

The outer structures are preferably designed to diffuse light, wherein alight-diffusing effect for the outer structures is provided in such away that a light band passing through the building envelope part iswidened by a factor of roughly three from the exterior side up to theinterior side. This type of configuration for the outer structures makesit comparatively easy to manufacture an efficient building envelope partwith light diffusers as the outer structures as described above.However, the mentioned expansion factor can also be differentlyconfigured depending on the situation, wherein it can range from 2 to 5,for example.

The outer structures and inner structures are preferably given alamellar design. For example, the term “lamellar” can be understood as aparallel arrangement of stripes in a plane, wherein these stripesexhibit straight sides and a specific width, for example. This type oflamellar configuration for the outer structures and inner structuresenables a comparatively simple, efficient construction and manufactureof the building envelope part.

Another aspect of the invention relates to a computer program, whichexhibits program code means configured to at least partially implementthe method described above when the computer program is run on acomputer. This type of computer program makes it possible tocomparatively easily, quickly and precisely carry out the methodaccording to the invention. In addition, this type of computer programmakes it possible to implement and distribute the method according tothe invention in an expedient and efficient manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The building envelope part according to the invention and the methodaccording to the invention will be described in greater detail belowwith reference to the attached drawings based upon exemplaryembodiments. Shown on:

FIG. 1 is a diagrammatic cross sectional view depicting part of a firstexemplary embodiment for a building envelope part according to theinvention;

FIG. 2 is a diagrammatic view on the building envelope part from FIG. 1,for example for an east-oriented façade for a latitude of the objectlocation measuring 45°;

FIG. 3 is a diagrammatic cross sectional view of the building envelopepart from FIG. 1 in a wintertime functional mode;

FIG. 4 is a diagrammatic cross sectional view of the building envelopepart from FIG. 1 in a summertime functional mode;

FIG. 5 is a diagrammatic cross sectional view depicting part of a secondexemplary embodiment for a building envelope part according to theinvention;

FIG. 6 is a diagrammatic cross sectional view depicting part of a thirdexemplary embodiment for a building envelope part according to theinvention;

FIG. 7 is a diagrammatic cross sectional view depicting part of a fourthexemplary embodiment for a building envelope part according to theinvention.

WAY(S) OF IMPLEMENTING THE INVENTION

FIG. 1 shows a glass pane 1 as a first exemplary embodiment of abuilding envelope part according to the invention with an outer surface2 and an inner surface 3 opposite the outer surface 2. The outer surface2 exhibits outer structures 21 with a fixed width, as well asintermediate outer regions 22 lying between the outer structures 21. Theinner surface 3 exhibits inner structures 31 with a fixed width, as wellas intermediate inner regions 32 lying between the inner structures 21.

The glass pane 1 is made out of a low-iron glass. The outer structures21 are formed by etching the glass pane 1, wherein the intermediateouter regions 22 are left unchanged. The inner structures 31 take theform of a mirror coating generated by means of a printed silver layer onthe glass pane 1, wherein the intermediate inner regions 32 are alsoleft unchanged.

The following stipulation applies with respect to the entire remainingdescription. If reference numbers are contained in a figure for purposesof graphic clarity, but not mentioned in the immediately accompanyingtext of the description, reference is made to their explanation inpreceding descriptions of figures. In addition, if reference numbers arementioned in a text of the description belonging directly to a figurebut not contained in the accompanying figure, reference is made to thepreceding figures.

FIG. 2 shows the glass pane 1 as viewed from outside. The outer surface2 and inner surface 3 are here bordered by four side edges 5. The glasspane 1 has a rectangular design. The outer structures 21 as well as theinner structures 31 of the glass pane 1 are configured as comparativelynarrow, parallel stripes, which run at differing inclinations dependingon the cardinal direction and location of a provided application for theglass pane 1. In other words, tailored to the respective circumstances,the parallel stripes or the outer structures 21 and inner structures 31define a more or less acute angle co with the side edges 5. The degreesof freedom are essentially as follows when configuring the parallelstripes: The width of the diffusely scattering stripes, i.e., of theouter structures 21, relative to the glass thickness; the width betweenthe diffusely scattering stripes, i.e., the intermediate outer regions22, relative to the glass thickness; the degree of diffusion for theouter structures 21 that defines the spatial dispersion of the incidentlight; the width of the mirroring stripes, i.e., of the innerstructures, relative to the glass thickness; the relative position ofdiffusely scattering to mirroring or absorbing stripes or of outerstructures to inner structures relative to the glass thickness; and theacute angle ω₁ at which the stripes run relative to the horizontal sideedge 5.

FIG. 3 shows how the glass pane 1 functions in winter. As evident, solarradiation 4 strikes the outer surface 2 of the glass pane 1 in aspecific first spatial angle of incidence range. The solar radiation 4is refracted at the intermediate outer regions 22 in a conventionalmanner in accordance with the refraction index of glass, and thenpenetrates through the glass pane 1 up until its inner surface 3. Thesolar radiation 4 is scattered on the outer structures 21, and againpenetrates through the glass pane 1 in the direction of the outersurface 2 or to the outside. The outer structures 21 are arrangedrelative to the inner structures 31 in such a way that allowscomparatively abundant solar radiation 4 to penetrate through the glasspane 1 directly through the intermediate outer regions 22 via theintermediate inner regions 32 through the glass pane 1. The scatteringeffect of the outer structures 21 also causes additional solar radiation4 to penetrate through the glass pane 1 via the intermediate innerregions 32 in the first spatial angle of incidence range, so thatcomparatively abundant solar radiation 4 can penetrate through the glasspane 1 in winter.

FIG. 4 shows how the glass pane 1 functions in summer. As evident, solarradiation 4 strikes the outer surface of the glass pane 1 in a specificsecond spatial angle of incidence range. The solar radiation 4 is againrefracted at the intermediate outer regions 22 in a conventional manner,and then penetrates through the glass pane 1 up until its inner surface3. The solar radiation 4 is scattered on the outer structures 21, andpenetrates through the glass pane 1 up until its inner surface 3. Thesolar radiation 4 is reflected on the inner structures 31, and thenpenetrates the glass pane 1 through the outer surface 2 toward theoutside. The outer structures 21 are arranged relative to the innerstructures 31 in such a way that comparatively little solar radiation 4can penetrate through the glass pane 1 directly through the intermediateouter regions 22 via the intermediate inner regions 32 through the glasspane 1. The scattering effect of the outer structures 21 also causesadditional solar radiation 4 to strike the reflecting inner structures31, so that comparatively little solar radiation 4 can penetrate throughthe glass pane 1 in summer.

FIG. 5 shows a glass pane 19 as a second exemplary embodiment of abuilding envelope part according to the invention with an outer surface29 and an inner surface 39 opposite the outer surface 29. The outersurface 29 exhibits outer structures 219 with a fixed width, as well asintermediate outer regions 229 that lie between the outer structures219. The inner surface 39 exhibits inner structures 319 with a fixedwidth, as well as intermediate inner regions 329 that lie between theinner structures 219.

The glass pane 19 is essentially designed to correspond to the glasspane 1 shown on FIG. 1 to FIG. 4. In particular, the glass panes 1, 19described above as well as those described below (see glass pane 18 onFIG. 6 and glass pane 17 on FIG. 7) are here preferably dimensioned andmanufactured via the following steps:

The axial rotation ω of any angle-selective outer and inner structuresis geared toward the orientation, i.e., the alignment and inclination,of the glass pane 1, 19, 18, 17 in its provided application, as well astoward the latitude of the object location at which the glass pane isbeing used. If the glass pane 1, 19, 18, 17 can receive direct solarradiation on all days in a calendar year, the longitudinal axis of theouter and inner structures must be aligned parallel to the intersectingline between the solar ecliptic and glass pane 1, 19, 18, 17, andotherwise perpendicular. The latter holds true in particular on thenorthern hemisphere in winter for glass panes 1, 19, 18, 17 or buildingenvelope parts aligned toward the north. The following relationshipapplies to glass panes 1, 19, 18, 17: A mathematical expression thatcorrelates the variables ω, β, γ and φ,

$\begin{matrix}{\omega = {{- {{sgn}\left( {\varphi*{\sin (\gamma)}} \right)}}*\arccos {\quad\left( \frac{{{\sin \left( {\varphi } \right)}*{\sin (\beta)}} + {{\cos \left( {\varphi } \right)}*{\cos (\beta)}*{\cos (\gamma)}}}{\sqrt{\begin{matrix}\left. {{{\cos \left( {\varphi } \right)}*{\cos (\beta)}} + {{\sin \left( {\varphi } \right)}*{\cos (\gamma)}*{\sin (\beta)}}} \right)^{2} \\{{+ {\sin^{2}(\gamma)}}*{\sin^{2}(\beta)}}\end{matrix}}} \right)}}} & (1)\end{matrix}$

In this case, β is an inclination of the glass pane 1, 19, 18, 17, γ isan alignment of the glass pane 1, 19, 18, 17, and φ is the latitude ofthe object location.

The angular dependence of the outer and inner structures in atransversal axial direction can be achieved in a variety of ways, forexample through the geometric or structural configuration of the glasspane 1, 19, 18, 17. As described above, the angle α₊ at which a maximumor minimum transmittance is to be achieved must first be determined forthis purpose given a parallel and perpendicular alignment. These twoangles are reached on June 21 and December 21, when the respective solarazimuth and alignment of the glass pane 1, 19, 18, 17 coincide, anddescribed by mathematical expressions that correlate the variablesα_(±), β, γ, ε and φ, preferably in accordance with the followingequations:

α_(±)=arcsin(cos(φ)*cos(γ))+(β−90°)±ε,  (2)

wherein ε≅23.4° is the obliqueness of the ecliptic relative to theequator, which is also referred to as the tilt of the earth's axis orobliquity. The outer structures and inner structures described above andbelow will be used in the following to illustrate configurations thatyield comparatively high contrast ratios for the angles α₊ (continuouslines) and α⁻ (broken lines).

In the glass pane on FIG. 4, stripes are applied as the outer structures219 to the outer surface 29 (air side) parallel to the longitudinal axisthrough printing, etching, sandblasting, roughening or in some otherway, and diffusely scatter the incident light or incident solarradiation 49. The sections between the stripes, i.e., the intermediateouter regions 229, are left unchanged. Stripes are also applied as theinner structures 319 on the inner surface 39 of the glass pane parallelto the longitudinal axis through printing or in some other way, andreflect or absorb the incident light or incident solar radiation 49. Thesections between the stripes, i.e., the intermediate inner regions 329,are left unchanged. The width and relative location of the upper andlower stripes, i.e., the outer structures 21 and inner structures 31, ofthe glass pane must be selected in such a way that the light fallingthrough the clear sections, i.e., the intermediate outer regions 229,from outside or above, in turn passes through the clear sections below,i.e., the intermediate inner regions 329, at the angle α₊ and the lightfalling through the clear sections, i.e., the intermediate outer regions229, from outside or above, in turn strikes the reflecting sectionsbelow, i.e., the inner structures 319, at the angle α⁻. The respectivelight refraction of the glass must here be taken into account by amathematical expression that correlates the variables r, d, α_(±) and n,preferably in accordance with the equation

$\begin{matrix}{{\frac{r}{d} = {\frac{\sin \left( \alpha_{+} \right)}{\sqrt{n^{2} - {\sin^{2}\left( \alpha_{+} \right)}}} - \frac{\sin \left( \alpha_{-} \right)}{\sqrt{n^{2} - {\sin^{2}\left( \alpha_{-} \right)}}}}},} & (3)\end{matrix}$

wherein d [mm] is the thickness of the glass or glass pane 19, r [mm] isthe width of the reflector or inner structures 319, and n is the averagerefraction index of glass. The second summand in the above equationindicates the offset in outer and inner structures x/d. The scatteringeffect of the diffuse stripes or outer structures 219 with width m [mm]must be selected in such a way as to widen the incident light band byabout a factor of three as it passes through the glass thickness.

FIG. 6 shows the glass pane 18 as a third exemplary embodiment of abuilding envelope part according to the invention with an outer surface28 and an inner surface 38 opposite the outer surface 28. The outersurface 28 exhibits prismatic outer structures 218 with a fixed width.The inner surface 38 exhibits inner structures 318 with a fixed width,as well as intermediate inner regions 328 that lie between the innerstructures 218. The outer structures 218 designed as flat prisms on theouter surface of the glass pane guide the light bands or solar radiationincident at angles α₊ or α⁻ in the direction of the reflectors or innerstructures 318 via light diffraction to a maximum or minimum extent.

FIG. 7 shows a glass pane 17 as a fourth exemplary embodiment of abuilding envelope part according to the invention with an outer surface27 and an inner surface 37 opposite the outer surface 27. The outersurface 27 exhibits outer structures 217, as well as intermediate outerregions 227 that lie between the outer structures 217. The outerstructures 217 protrude through the glass pane 17, and extend from theouter surface 27 up until the inner surface 37. The inner surface 37exhibits inner structures 317 with a fixed width, as well asintermediate inner regions 327 that lie between the inner structures217. The outer structures 217 are each joined with one of the innerstructures 317, so that they together each exhibit an essentiallyL-shaped cross section.

The outer structures 217 and inner structures 317 designed as L-shapedlamellae allow the light bands or solar radiation 47 incident at anglesα₊ or α⁻ to be maximally passed through or reflected by the constructionor glass pane 17 owing to reflections. In the case of

α₊=−α⁻  (4)

where x=0 mm, the contrast ratio is maximal (full transmittance or fullreflection). At

$\begin{matrix}{\frac{x}{d} = {\sin \left( {\left( {\alpha_{+} + \alpha_{-}} \right)/4} \right)}} & (5)\end{matrix}$

an optimal contrast ratio is reached for α₊≠−α⁻.

Even though the invention was depicted and detailed based on the figuresand accompanying specification, this depiction and detailed descriptionmust be regarded as illustrative and exemplary, and not construed aslimiting the invention. It goes without saying that a person skilled inthe art can introduce changes and modifications without departing fromthe scope and spirit of the following claims. In particular, theinvention also encompasses embodiments with any combination of featuresmentioned or shown above or below in relation to various embodiments.For example, the invention can also be realized by the followingadditional variations in structural design:

-   -   Given an analogue construction as described above with respect        to FIG. 5, using light-polarized stripes as outer structures and        inner structures that are complementarily polarized for c and r,        the transmittance can be maximal at an angle α₊ and drop off        approximately or entirely to zero at an angle α⁻.    -   The disclosed arrangements and configurations of outer        structures and inner structures, in particular those described        above on FIG. 5, FIG. 6 and FIG. 7, can advantageously also be        arranged in such a way as not to form an acute angle with one of        the side edges. They can also be situated horizontally.

The invention also encompasses individual features in the figures, evenif they are there shown in conjunction with other features and/or notmentioned above or below. In addition, the subject matter of theinvention can exclude the alternative embodiments described in thefigures and specification, and individual alternative features thereof.

Furthermore, the term “encompass” or “comprise” and derivations thereofdoes not preclude other elements or steps. Likewise, the indeterminatearticle “a” or “an” and derivations thereof does not rule out aplurality. The functions of several features enumerated in the claimscan be satisfied by a single unit. In particular, the terms“essentially”, “roughly”, “approximately” and the like in conjunctionwith a property or value also precisely define the property or preciselydefine the value. A computer program can be stored and/or run on asuitable medium, for example on an optical storage medium or a fixedmedium, which is provided together with or as part of other hardware. Itcan also be run in another form, for example via the internet or otherwired or wireless telecommunication systems. In particular, for example,a computer program can be a computer program product that is stored on acomputer-readable medium, and designed to be executed to implement amethod, especially the method according to the invention. All referencenumbers in the claims are not to be construed as limiting the scope ofthe claims.

1. A building envelope part (1; 17; 18; 19) for angle-selectiveirradiation insulation, wherein the building envelope part (1; 17; 18;19) comprises an outer surface (2; 27; 28; 29) with outer structures(21; 217; 218; 219), an inner surface (3; 37; 38; 39) opposite the outersurface (2; 27; 28; 29) with inner structures (31; 317; 318; 319) and aside edge (5) that borders the outer surface (2; 27; 28; 29) and innersurface (3; 37; 38; 39), wherein the outer structures (21; 217; 218;219) and inner structures (31; 317; 318; 319) are arranged relative toeach other in such a way that the translucency of the building envelopepart (1; 17; 18; 19) varies as a function of the spatial angle ofincidence, characterized in that the outer structures (21; 217; 218;219) and inner structures (31; 317; 318; 319) are arranged at an acuteangle to the side edge (5).
 2. The building envelope part (1; 17; 18;19) according to claim 1, in which the outer structures (21; 217; 218;219) are arranged as light diffusers, and the inner structures (31; 317;318; 319) are arranged as optically opaque.
 3. The building envelopepart (1; 17; 18; 19) according to claim 1, in which the outer structures(21; 217; 218; 219) are prismatic, and the inner structures (31; 317;318; 319) are optically opaque in design.
 4. The building envelope part(1; 17; 18; 19) according to claim 2 or 3, in which the inner structures(31; 317; 318; 319) are designed as light reflectors.
 5. The buildingenvelope part (1; 17; 18; 19) according to claim 2 or 3, in which theinner structures (31; 317; 318; 319) are arranged as light absorbers,wherein the light absorbers are photovoltaic light absorbers.
 6. Thebuilding envelope part (1; 17; 18; 19) according to claim 1, in whichthe outer structures (21; 217; 218; 219) comprise parallel stripesarranged in a common plane, and the inner structures (31; 317; 318; 319)comprise parallel stripes arranged in a common plane.
 7. The buildingenvelope part (1; 17; 18; 19) according to claim 6, in which the outerstructures (21; 217; 218; 219) are arranged parallel to the innerstructures (31; 317; 318; 319), wherein the common plane of the outerstructures (21; 217; 218; 219) and the common plane of the innerstructures (31; 317; 318; 319) are different.
 8. The building envelopepart (1; 17; 18; 19) according to claim 1, in which the outer structures(21; 217; 218; 219) are arranged in a direction perpendicular to theouter surface (2; 27; 28; 29) and to the inner surface (3; 37; 38; 39),offset in relation to the inner structures (31; 317; 318; 319).
 9. Thebuilding envelope part (1; 17; 18; 19) according to claim 1, in whichthe outer structures (21; 217; 218; 219) and inner structures (31; 317;318; 319) are essentially lamellar in design.
 10. A method formanufacturing a building envelope part (1; 17; 18; 19) forangle-selective irradiation insulation, wherein the building envelopepart (1; 17; 18; 19) comprises an outer surface, an inner surface (3;37; 38; 39) opposite the outer surface (2; 27; 28; 29), and a side edge(5) that borders the outer surface (2; 27; 28; 29) and inner surface (3;37; 38; 39), in which the outer surface (2; 27; 28; 29) is provided withouter structures (21; 217; 218; 219) and the inner surface (3; 37; 38;39) is provided with inner structures (31; 317; 318; 319), wherein theouter structures (21; 217; 218; 219) and inner structures (31; 317; 318;319) are arranged relative to each other in such a way that thetranslucency of the building envelope part (1; 17; 18; 19) varies as afunction of the spatial angle of incidence, characterized in that theouter structures (21; 217; 218; 219) and inner structures (31; 317; 318;319) are arranged taking into account the orientation of a providedapplication of the building envelope part (1; 17; 18; 19) and takinginto account the latitude of the provided application of the buildingenvelope part (1; 17; 18; 19).
 11. The method according to claim 10, inwhich the longitudinal axes of the outer structures (21; 217; 218; 219)and inner structures (31; 317; 318; 319) are aligned parallel to anintersecting line between the plane of the solar ecliptic and the planeof the building envelope part (1; 17; 18; 19) in the providedapplication if the building envelope part (1; 17; 18; 19) can be reachedby direct solar radiation on all days of a calendar year in the providedapplication.
 12. The method according to claim 11, in which the acuteangle between the outer structures (21; 217; 218; 219) and side edge (5)or between the inner structures (31; 317; 318; 319) and side edge (5) isestablished by a mathematical expression that correlates the variablesω, β, γ and φ, preferably according to the equation$\omega = {{- {{sgn}\left( {\varphi*{\sin (\gamma)}} \right)}}*\arccos {\quad\left( \frac{{{\sin \left( {\varphi } \right)}*{\sin (\beta)}} + {{\cos \left( {\varphi } \right)}*{\cos (\beta)}*{\cos (\gamma)}}}{\sqrt{\left. {{{\cos \left( {\varphi } \right)}*{\cos (\beta)}} + {{\sin \left( {\varphi } \right)}*{\cos (\gamma)}*{\sin (\beta)}}} \right)^{2} + {{\sin^{2}(\gamma)}*{\sin^{2}(\beta)}}}} \right)}}$wherein ω is the acute angle, β is an inclination, and γ is an alignmentof the building envelope part (1; 17; 18; 19) in the providedapplication, and φ is the latitude in the provided application.
 13. Themethod according to claim 10, in which a first projected angle ofincidence with a maximum light transmittance through the buildingenvelope part (1; 17; 18; 19) is established.
 14. The method accordingto claim 10, in which a second projected angle of incidence with aminimum light transmittance through the building envelope part (1; 17;18; 19) is established.
 15. The method according to claim 13, in whichthe building envelope part (1; 17; 18; 19) is configured in such a waythat the outer structures (21; 217; 218; 219) comprises parallel stripesarranged in a common plane, and the inner structures (31; 317; 318; 319)comprises parallel stripes arranged in a common plane.
 16. The methodaccording to claim 15, in which the building envelope part (1; 17; 18;19) is configured in such a way that the outer structures (21; 217; 218;219) are arranged parallel to the inner structures (31; 317; 318; 319),wherein the common plane of the outer structures (21; 217; 218; 219) andthe common plane of the inner structures (31; 317; 318; 319) aredifferent, and that the stripes of the outer structures (21; 217; 218;219) and stripes of the inner structures (31; 317; 318; 319) areestablished by a mathematical expression that correlates the variablesr, d, α_(±) and n, preferably according to the equation${\frac{r}{d} = {\frac{\sin \left( \alpha_{+} \right)}{\sqrt{n^{2} - {\sin^{2}\left( \alpha_{+} \right)}}} - \frac{\sin \left( \alpha_{-} \right)}{\sqrt{n^{2} - {\sin^{2}\left( \alpha_{-} \right)}}}}},$wherein r is the width of one of the stripes of the inner structures(31; 317; 318; 319), d is the thickness of the building envelope part(1; 17; 18; 19), n is the average refraction index of the buildingenvelope part (1; 17; 18; 19), α₊ is the first projected angle ofincidence, and α⁻ is the second projected angle of incidence.
 17. Themethod according to claim 15, in which the building envelope part (1;17; 18; 19) is configured in such a way that a width of the stripes ofthe exterior side, a width of the stripes of the interior side, and arespective distance between the stripes are essentially identicallydimensioned.
 18. A computer program comprising a program code structureconfigured to implement the method according to claim 10 when beingexecuted on a computer.
 19. A computer program comprising a program codestructure configured to implement the method according to claim
 11. 20.A computer program comprising a program code structure configured toimplement the method according to claim 12.